Silicon-containing polymer, negative type resist composition comprising the same, and patterning method for semiconductor device using the same

ABSTRACT

A polymer used for a negative type resist composition having a first repeating unit of a Si-containing monomer unit, a second repeating unit having a hydroxy group or an epoxy ring and copolymerized with the first repeating unit is provided. The first repeating unit is represented by the following formula:  
                 
 
     wherein R 1  is a hydrogen atom or a methyl group, X is a C 1 -C 4  alkyl or alkoxy group, and n is an integer from 2 to 4. Also, there is provided a negative type resist composition including the polymer which is an alkali soluble base polymer, a photoacid generator and a crosslinking agent cross linkable in the presence of an acid.

BACKGROUND

[0001] 1. Technical Field

[0002] The present invention relates generally to silicon-containingpolymers, negative type resist compositions comprising the same, and apatterning method for semiconductor devices using the same. Moreparticularly, the present invention relates to silicon-containingpolymers for use in a bi-layer resist (BLR) process, negative typeresist compositions comprising the same, and a patterning method forsemiconductor devices using the same.

[0003] 2. Discussion of the Related Art

[0004] As semiconductor devices become more highly integrated andcomplex, the ability to form ultra-fine patterns becomes more important.For instance, in semiconductor devices of 1-Gigabit or greater, apattern size having a design rule of 0.2 μm or less is needed. Suchpattern size is difficult to achieve using conventional lithographyprocesses using lower wavelength devices, e.g., a KrF eximer laser (248nm), with a conventional resist material. Lithography processes usingdifferent exposure light sources, e.g., ArF excimer laser (193 nm) or F₂excimer laser (157 nm), have been proposed.

[0005] Further, conventional ArF or F₂ resist materials suffer from avariety of drawbacks due to their structural limitation. One problem isthe increase in the occurrence of patterns collapsing as the aspectratio of pattern features increases. Another problem is the weakresistance against a dry etching process. Accordingly, there is anincreasing demand for the development of new resist materials andprocesses.

[0006] In photolithography for the manufacture of highly integratedsemiconductor devices, a single layer resist (SLR) process and abi-layer resist (BLR) process are widely used. Use of the BLR processovercomes problems associated with the SLR process. For example, the BLRprocess increases the resistance to dry etching. Therefore, patternshaving large aspect ratios can be formed using the BLR process and highresolution power can be provided at short-wavelength regions.

[0007] Generally, a BLR process requires a two component chemicallyamplified resist comprising a silicon-containing polymer having asilicon atom substituted in the backbone of the polymer and a photoacidgenerator (PAG), which is a positive type chemically amplified resist.Also, high-sensitivity resist materials suitable for the BLR processdeveloped to be compatible with short-wavelength light sources aremostly positive type chemically amplified resists.

[0008] Although positive type chemically amplified resists are preferredin view of their higher resolution, compositions synthesized from thepositive type chemically amplified resists suitable for the BLR processare too hydrophobic. Thus, adhesion to underlying layer materials isweak, and it is difficult to control the amount of silicon needed tocreate suitable resist materials. In particular, the most seriousproblem with the positive type chemically amplified resists is shrinkageby e-beam. In other words, while observing sizes of resist patternsusing a scanning electron microscope (SEM), critical dimensions (CDs) ofthe patterns may change.

[0009] In pursuit of high-speed, highly-efficient DRAMs, there is alimitation in using positive type resists for forming isolated patterns.In lithography processes for the manufacture of semiconductor deviceshaving a memory capacity of 1-Gigabit or more, use of phase shift masksis needed. In the design of phase shift masks, negative type resists arepreferred over positive type resists.

[0010] Therefore, there is a need to develop negative type resistshaving a high transmittance to short-wavelength exposure light sources,high resolution power, and high dry etching resistance.

SUMMARY OF THE INVENTION

[0011] Provided is a polymer having a high transmittance atshort-wavelengths and a high dry etching resistance for the manufactureof negative type resist compositions for forming fine patterns in ahighly integrated semiconductor device.

[0012] Also provided is a negative type resist composition that can beused in conjunction with KrF eximer laser (248 nm), ArF excimer laser(193 nm) and next-generation F₂ excimer laser (157 nm), which alsoprovides high dry etching resistance by including silicon and can beadvantageously used in a BLR process to realize high resolution powerand large aspect ratios.

[0013] Further, provided is a patterning method for a semiconductordevice, by which fine patterns having large aspect ratios can be formedin highly integrated semiconductor devices.

[0014] According to one aspect of the present invention, there isprovided a polymer used for a negative type resist composition,represented by the following formula:

[0015] wherein R₁ is a hydrogen atom or methyl group, R₂ is a C₂˜C₈alkyl group having a hydroxy group, R₃ is a hydrogen atom or methylgroup, X is a C₁-C₄ alkyl or alkoxy group, n is an integer from 2 to 4,and q/(p+q) is about 0.1 to about 0.5. And, the weight average molecularweight of the polymer is about 3,000 to about 50,000.

[0016] Preferably, R₂ is a 2-hydroxyethyl or a 2-hydroxypropyl group andX is a methyl group or a trimethylsilyloxy group. Further, the polymermay also include at least one repeating unit selected from the groupconsisting of acrylate derivatives, methacrylate derivatives, norbornenederivatives, maleic anhydride monomer derivatives and styrenederivatives, and the Si-containing repeating unit is contained in thebase polymer in an amount of about 5 to about 40 mol % based on totalnumber of moles of repeating units forming the base polymer.

[0017] In another aspect of the present invention, there is provided apolymer used for a negative type resist composition, represented by thefollowing formula:

[0018] wherein R₁ is a hydrogen atom or a methyl group, R₂ is a hydrogenatom or methyl group, X is a C₁-C₄ alkyl or alkoxy group, n is aninteger from 2 to 4, and q/(p+q) is about 0.1 to about 0.5. And, theweight average molecular weight of the polymer is about 3,000 to about50,000.

[0019] Preferably, X is a methyl group or a trimethylsilyloxy group.Further, the polymer may also include at least one repeating unitselected from the group consisting of acrylate derivatives, methacrylatederivatives, norbornene derivatives, maleic anhydride monomerderivatives and styrene derivatives, and wherein the Si-containingrepeating unit is contained in the base polymer in an amount of about 5to about 40 mol % based on total number of moles of repeating unitsforming the base polymer.

[0020] According to still another aspect of the present invention, thereis provided a negative type resist composition comprising:

[0021] (a) an alkali soluble base polymer having a first repeating unitrepresented by the following formula:

[0022] wherein R₁ is a hydrogen atom or methyl group, X is a C₁-C₄ alkylor alkoxy group, and n is an integer from 2 to 4, a photoacid generator(PAG), and a crosslinking agent cross linkable in the presence of anacid. Further, the base polymer has a weight average molecular weight ofabout 3,000 to about 50,000.

[0023] According to yet another aspect of the present invention, thereis provided a patterning method for a semiconductor device comprisingforming a first resist layer on a layer to be etched on a semiconductorsubstrate, forming a second resist layer by coating a negative typeresist composition comprising an alkali soluble base polymer, pre-bakingthe second resist layer, exposing the second resist layer to light,performing post-exposure baking (PEB) on the exposed second resistlayer, forming a second resist layer pattern by developing the exposedsecond resist layer, forming a first resist layer pattern by etching thefirst resist layer using the second resist layer pattern as an etchingmask, and etching the layer to be etched using the first resist layerpattern as an etching mask.

[0024] Further, the negative type resist composition comprising analkali soluble base polymer may be represented by the following formula:

[0025] wherein R₁ is a hydrogen atom or a methyl group, R₂ is a hydrogenatom or methyl group, X is a C₁-C₄ alkyl or alkoxy group, n is aninteger from 2 to 4, and q/(p+q) is about 0.1 to about 0.5, a photoacidgenerator (PAG), and a crosslinking agent formed of a compound having ahydroxy group and cross linkable by reacting with an acid.

[0026] Thus, a polymer, a negative type photoresist, and a patterningmethod for semiconductor devices using the same to solve the problems ofthe conventional art are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIGS. 1 through 4 are cross-sectional views of a patterning methodfor semiconductor devices, according to an exemplary embodiment of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0028] The Embodiments of the present invention will now be describedmore fully hereinafter with reference to the accompanying drawings whereapplicable, in which preferred embodiments of the invention are shown.This invention may, however, be embodied in different forms and shouldnot be construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the invention to thoseskilled in the art.

[0029] A negative type resist composition according to an exemplaryembodiment of the present invention includes an alkali soluble basepolymer having a repeating unit formed of a Si-containing monomer unit,a photoacid generator (PAG) and a crosslinking agent cross linkable byreacting with an acid.

[0030] The base polymer comprises a first repeating unit represented byFormula 1:

[0031] wherein R₁ is a hydrogen atom or a methyl group, X is a C₁-C₄alkyl or alkoxy group, and n is an integer from 2 to 4. The base polymerhas a weight average molecular weight of about 3,000 to about 50,000.

[0032] Preferably, X is a methyl group or a trimethylsilyloxy group.

[0033] The base polymer may further include a second repeating unithaving a hydroxy group represented by Formula 2:

[0034] wherein R₂ is a hydrogen atom or a methyl group, R₃ is a C₂˜C₈alkyl group having a hydroxy group. Preferably, R₃ is a 2-hydroxyethylor a 2-hydroxypropyl group.

[0035] If the base polymer includes a Si-containing first repeating unitrepresented by Formula 1 and a second repeating unit having a hydroxygroup represented by Formula 2, the structure of the base polymer can berepresented by Formula 3:

[0036] wherein R₁ is a hydrogen atom or a methyl group, R₂ is a C₂˜C₈alkyl group having a hydroxy group, R₃ is a hydrogen atom or a methylgroup, X is a C₁-C₄ alkyl or alkoxy group, n is an integer from 2 to 4,and q/(p+q) is about 0.1 to about 0.5. Preferably, R₂ is a2-hydroxyethyl group or a 2-hydroxypropyl group.

[0037] In the case of using the base polymer represented by Formula 3, anegative type resist composition can be manufactured using a compoundhaving an epoxy ring as a crosslinking agent. In the manufacture of thenegative type resist composition, aliphatic compounds having multi-epoxygroups can be used as the crosslinking agent having an epoxy ring. Thesealiphatic compounds cause curing with a hydroxy group in the presence ofan acid.

[0038] Preferably, the crosslinking agent having an epoxy ring is atriglycidyl isocyanurate, a trimethylolpropane triglycidyl ether, or atriphenylolmethane triglycidyl ether.

[0039] The base polymer represented by Formula 3 may further include athird repeating unit selected from the group consisting of acrylatederivatives, methacrylate derivatives, norbornene derivatives, maleicanhydride monomer derivatives, and styrene derivatives. Preferably, theSi-containing repeating unit is contained in the base polymer in anamount of about 5 to about 40 mol % based on total number of moles ofrepeating units forming the base polymer.

[0040] The second repeating unit may be a repeating unit having an epoxyring represented by the following Formula 4:

[0041] wherein R₄ is a hydrogen atom or a methyl group.

[0042] If the base polymer includes a Si-containing first repeating unitrepresented by Formula 1 and a second repeating unit having an epoxyring represented by Formula 4, the structure of the base polymer can berepresented by Formula 5:

[0043] wherein R₁ is a hydrogen atom or a methyl group, R₂ is a hydrogenatom or a methyl group, X is a C₁-C₄ alkyl or alkoxy group, n is aninteger from 2 to 4, and q/(p+q) is about 0.1 to about 0.5.

[0044] In the case of using the base polymer represented by Formula 5, anegative type resist composition can be manufactured using a compoundhaving a hydroxy group as a crosslinking agent, according to anotherembodiment of the present invention. In the manufacture of the negativetype resist composition, the crosslinking agent having a hydroxy groupused for causing curing with an expoxy ring in the base polymer may be apolymer having three or more different monomer units. In addition, thecrosslinking agent may be a low molecular weight aliphatic compoundhaving a multi-hydroxy group, and the low-molecule weight aliphaticcompound may cause curing with an epoxy group in the presence of anacid.

[0045] Preferably, the crosslinking agent having a hydroxy group is1,3,5-tris(2-hydroxyethyl)cyanuric acid,1,1,1-tris(hydroxymethyl)ethane, triethylene glycol, diethylene glycol,1,2,6-trihydroxyhexane or trimethylolpropane.

[0046] The base polymer represented by Formula 5 may further include athird repeating unit selected from a group consisting of acrylatederivatives, methacrylate derivatives, norbornene derivatives, maleicanhydride monomer derivatives and styrene derivatives. Preferably, theSi-containing repeating unit is contained in the base polymer in anamount of about 5 to about 40 mol % based on total number of moles ofrepeating units forming the base polymer. Preferably, the thirdrepeating unit includes a (meth)acrylate derivative or norbornenederivative having a hydroxy group.

[0047] In the manufacture of the negative type resist compositionaccording to another exemplary embodiment of the present invention, PAGis contained in an amount of about 1.0 to about 15% by weight based onthe total weight of the base polymer. Preferably, PAG includes oniumcompounds exemplified by triarylsulfonium salts, diaryliodonium salts,or mixtures thereof. More preferably, the PAG comprisestriphenylsulfonium triflate, diphenyliodonium triflate,di-t-butyldiphenyliodonium triflate, or mixtures thereof.

[0048] According to another embodiment of the present invention, anegative type resist composition may further comprise an organic base inan amount of about 0.01 to about 2.0 wt % on the basis of the totalweight of the base polymer. Preferably, the organic base comprisesorganic tertiary amine compounds exemplified by triethylamine,triisobutylamine, trioctylamine, triisodecylamine, triethanolamine, ormixtures thereof.

[0049]FIGS. 1 through 4 are cross-sectional views of a patterning methodfor a semiconductor device according to the present invention.

[0050] First, referring to FIG. 1, an etching target layer 12 is formedon a substrate 10, for example, a semiconductor substrate or atransparent, and a BLR structure resist layer comprised of a firstresist layer 22 and a second resist layer 24 containing silicon isformed by spin coating. The second resist layer 24 is a negative typeresist composition according to the embodiments of the present inventiondiscussed above. After the negative type resist composition is spincoated on the first resist layer 22, pre-baking is performed to providethe second resist layer 24 having a predetermined thickness. Preferably,the predetermined thickness of the second resist layer 24 is about 100to about 400 nm.

[0051] Referring to FIG. 2, a selected portion of the second resistlayer 24 is exposed to light through a mask 26 using a KrF, ArF or F₂eximer laser. Thus, the second resist layer 24 is defined by an exposureportion 24 a and a non-exposure portion 24 b. Then, a post exposure bake(PEB) is performed on the exposed second resist layer 24. And,cross-linkage occurs at the exposure portion 24 a of the second resistlayer 24 with the PAG.

[0052] Referring to FIG. 3, the exposed second resist layer 24 isdeveloped using an alkali solution, e.g., a tetramethylammoniumhydroxide (TMAH) solution, to remove the non-exposure portion 24 b,thereby forming a second resist layer pattern 24 a formed of theexposure portion 24 a, which is a negative type pattern.

[0053] Referring to FIG. 4, the first resist layer 22 is etched, e.g.,using O₂ plasma, using the second resist layer pattern 24 a as anetching mask to form a first resist layer pattern 22 a. Subsequently,the etching target layer 12 is etched using the first resist layerpattern 22 a as an etching mask to form an etching target layer pattern12 a.

[0054] The present invention will now be described in more detail withreference to the following illustrative examples. Further, the followingillustrative examples may be altered in various forms and the inventionshould not be construed as limited thereto.

EXAMPLE 1 Synthesis of Polymer

[0055]

[0056] 4.3 g of 3-[tris(trimethylsilyloxy)silyl]propyl methacrylate (10mmol) and 3.9 g of 2-hydroxyethyl methacrylate (30 mmol) were dissolvedin a round bottom flask containing 35 g of tetrahydrofuran (THF) and0.33 g of azobisisobutyronitrile (AIBN) (5 mol %) and purged usingnitrogen, followed by polymerizing at about 65° C. for about 12 hours.

[0057] After polymerization, the reactant was slowly precipitated withexcess n-hexane. Thereafter, the precipitate was filtered, and thefiltrate was dissolved in an appropriate amount of THF andre-precipitated in n-hexane. Then, the obtained precipitate was dried ina vacuum oven at about 50° C. for about 24 hours, giving a desiredproduct at a yield of about 75%.

[0058] The obtained product had a weight average molecular weight (Mw)of about 13,200 and polydispersity (Mw/Mn) of about 1.9.

EXAMPLE 2 Synthesis of Polymer

[0059]

[0060] 1.8 g of 4-hydroxystyrene (15 mmol), 2.0 g of 2-hydroxyethylmethacrylate (15 mmol), and 4.3 g of3-[tris(trimethylsilyloxy)silyl]propyl methacrylate (10 mmol) weredissolved 30 g of THF and 0.33 g of AIBN (5 mol %), followed bypolymerizing, thereby synthesizing a desired polymer at a yield of about70%.

[0061] The obtained product had a weight average molecular weight (Mw)of about 12,100 and polydispersity (Mw/Mn) of about 2.0.

EXAMPLE 3 Synthesis of Polymer

[0062]

[0063] 2.6 g of 2-hydroxyethyl methacrylate (20 mmol), 2.95 g of maleicanhydride (30 mmol) and 4.3 g of 3-[tris(trimethylsilyloxy)silyl]propylmethacrylate (10 mmol) were dissolved in 20 g of THF and 0.20 g of AIBN(2 mol %), followed by polymerizing, thereby synthesizing a desiredpolymer at a yield of about 50%.

[0064] The obtained product had a weight average molecular weight (Mw)of about 9,700 and polydispersity (Mw/Mn) of about 1.9.

EXAMPLE 4 Synthesis of Polymer

[0065]

[0066] 4.3 g of 3-[tris(trimethylsilyloxy)silyl]propyl methacrylate (10mmol) and 5.7 g of glycidyl methacrylate (40 mmol) were dissolved in around bottom flask containing 40 g of THF and 0.41 g of AIBN (5 mol %)and purged using nitrogen, followed by polymerizing at about 65° C. forabout 12 hours.

[0067] After polymerization, the reactant was slowly precipitated withexcess n-hexane. Thereafter, the precipitate was filtered, and thefiltrate was dissolved in an appropriate amount of THF andre-precipitated in n-hexane. Then, the obtained precipitate was dried ina vacuum oven at about 50° C. for about 24 hours, giving a desiredproduct at a yield of about 75%.

[0068] The obtained product had a weight average molecular weight (Mw)of about 13,500 and polydispersity (Mw/Mn) of about 2.0.

EXAMPLE 5 Synthesis of Polymer

[0069]

[0070] 2.2 g of glycidyl methacrylate (15 mmol), 2.0 g of 2-hydroxyethylmethacrylate (15 mmol) and 4.3 g of3-[tris(trimethylsilyloxy)silyl]propyl methacrylate (10 mmol) weredissolved in 30 g of THF and 0.33 g of AIBN (5 mol %), followed bypolymerizing in the same manner as in Example 4, thereby synthesizing adesired polymer at a yield of about 70%.

[0071] The obtained product had a weight average molecular weight (Mw)of about 14,100 and polydispersity (Mw/Mn) of about 2.0.

EXAMPLE 6 Synthesis of Polymer

[0072]

[0073] 4.4 g of glycidyl methacrylate (30 mmol), 3.95 g of maleicanhydride (40 mmol) and 4.3 g of 3-[tris(trimethylsilyloxy)silyl]propylmethacrylate (10 mmol) were dissolved in 25 g of THF together with 0.26g of AIBN (2 mol %), followed by polymerizing in the same manner as inExample 1, thereby synthesizing a desired polymer at a yield of about50%.

[0074] The obtained product had a weight average molecular weight (Mw)of about 9,100 and polydispersity (Mw/Mn) of about 1.9.

EXAMPLE 7 Preparation of Resist Compositions and LithographicPerformance

[0075] Using polymers synthesized in Examples 1 through 3 as basepolymers, 1.0 g of each polymer, 0.2 g of trimethylolpropane triglycidylether as a crosslinking agent, 0.02 g of triphenylsulfoniumtrifluoromethane sulfonate (triflate) as a PAG and 1 mg triisobutylamineas an organic base were completely dissolved in 10 g of propylene glycolmonomethyl ether acetate (PGMEA) and then filtered using a 0.2 μmmembrane filter, thereby forming each resist solution. The filteredsolution was then coated to a thickness of about 0.25 μm on a baresilicon (Si) wafer treated with hexamethyldisilazane (HMDS), a pre-bake(or soft-bake) was performed at about 120° C. for about 90 seconds andexposed to light using an ArF stepper (0.6 NA, σ=0.75).

[0076] Then, a post exposure bake (PEB) was performed at a temperatureof about 120° C. for about 60 seconds. The resultant was developed usinga solution of 2.38 wt % tetramethylammonium hydroxide (TMAH) for about60 seconds. Thus, a 150 nm line-and-space pattern was obtained at anexposure dose of about 11 to about 15 mJ/cm².

EXAMPLE 8 Preparation of Resist Compositions and LithographicPerformance

[0077] Using polymers synthesized in Examples 1 through 3 as basepolymers, 1.0 g of each polymer, 0.2 g triglycidyl isocyanurate as acrosslinking agent and 0.02 g triphenylsulfonium trifluoromethanesulfonate (triflate) as a PAG were completely dissolved in 10 g PGMEAand then filtered using a 0.2 μm membrane filter, thereby forming eachresist solution. The filtered solution was coated to a thickness ofabout 0.25 μm on a bare silicon (Si) wafer treated with HMDS, asoft-bake was performed at about 120° C. for about 90 seconds, and thenexposed to light using an ArF stepper (0.6 NA, σ=0.75).

[0078] Next, a PEB was performed at a temperature of about 120° C. forabout 60 seconds. The resultant was developed using a solution of TMAH(2.38 wt %) for about 60 seconds. Thus, a 150 nm line-and-space patternwas obtained at an exposure dose of about 10 to about 16 mJ/cm².

EXAMPLE 9 Preparation of Resist Composition and Lithographic Performance

[0079] 1.0 g of each of the respective polymers synthesized in Examples4 and 6 as a base polymer, 0.2 g of 1,3,5-tris(2-hydroxyethyl)cyanuricacid as a crosslinking agent and 0.02 g of triphenylsulfonium triflateas a PAG were completely dissolved in 10.0 g of propylene glycolmonomethyl ether acetate (PGMEA) and then filtered using a 0.2 μmmembrane filter, thereby forming each resist solution.

[0080] A resist solution was then coated to a thickness of about 0.25 μmon a silicon (Si) wafer treated with HMDS, and pre-baked at about 120°C. for about 90 seconds, followed by exposing to light using an ArFstepper (0.6NA, σ=0.75). Thereafter, a post exposure bake (PEB) wasperformed at a temperature of about 120° C. for about 60 seconds.

[0081] The resultant was developed using a solution of TMAH (2.38 wt %)for about 60 seconds. Thus, a 150 nm line-and-space pattern was obtainedat an exposure dose of about 11 to about 15 mJ/cm².

EXAMPLE 10 Preparation of Resist Composition and LithographicPerformance

[0082] 1.0 g of a polymer synthesized in Example 5 as a base polymer,0.2 g of 1,3,5-tris(2-hydroxyethyl)cyanuric acid as a crosslinkingagent, triisobutylamine amine as an organic solvent and 0.02 g oftriphenylsulfonium triflate as a PAG were completely dissolved in 10.0 gof propylene glycol monomethyl ether acetate (PGMEA) and then filteredusing a 0.2 μm membrane filter, thereby forming a resist solution.

[0083] The resist solution was then coated to a thickness of about 0.25μm on a silicon (Si) wafer treated with HMDS, and pre-baked at about120° C. for about 90 seconds, followed by exposure to light using an ArFstepper (0.6NA, σ=0.75).

[0084] Thereafter, a post exposure bake (PEB) was performed at atemperature of about 120° C. for about 60 seconds. The resultant wasdeveloped using a solution of TMAH (2.38 wt %) for about 60 seconds.Thus, a 140 nm line-and-space pattern was obtained at an exposure doseof about 10 to about 16 mJ/cm².

EXAMPLE 11 BLR Patterning Process

[0085] A silicon nitride layer is formed on a Si wafer to a thickness ofabout 3000 Å and an i-line resist (such as ip3300 manufactured by TokyoOhka Kogyo Co.) was coated thereon to a thickness of about 500 nm,followed by thermally treating the Si wafer having the silicon nitridelayer and i-line resist at a temperature of about 220° C., therebyforming a bottom layer.

[0086] The resist composition (Example 4) obtained from the polymersynthesized in Example 3 was coated on the bottom layer to a thicknessof about 250 nm to form a top layer. Thereafter, a soft-bake wasperformed at about 120° C. for about 90 seconds. Then, an exposureprocess was performed using an ArF stepper (0.6NA, σ=0.75). Next, a postexposure bake (PEB) was performed at a temperature of about 120° C. forabout 60 seconds. The resultant was then developed using a solution ofTMAH (2.38 wt %) for about 60 seconds. Next, a post-development bake(PDB) was performed at about 110° C. for about 60 seconds to form a toplayer pattern.

[0087] The bottom layer was etched by a dry etching process using O₂plasma (source gases: O₂/SO₂) and the top layer pattern as an etchingmask to form a bottom layer pattern. Thereafter, the top layer patternwas removed using a stripper.

[0088] Thereafter, a silicon nitride layer was etched by a dry etchingprocess using a CF₄ plasma and the bottom layer pattern comprised ofi-line resist as an etching mask, thereby forming a silicon nitridelayer pattern. Then, the resist layer remaining on the wafer was removedusing a stripper.

[0089] Although the present invention has been particularly shown anddescribed with reference to specific embodiments thereof, thenon-limiting embodiments described in the specification of the inventionare illustrative only.

[0090] For example, in the manufacture of a negative type resistcomposition according to the present invention, the crosslinking agentis not limited to the compounds illustrated in the embodiments. Forexample, as in Examples 7 and 8, triglycidyl isocyanurate,trimethylolpropane triglycidyl ether or triphenylolmethane triglycidylether can also be used as a crosslinking agent. Also, as in Examples 9and 10, 1,3,5-tris(2-hydroxyethyl)cyanuric acid,1,1,1-tris(hydroxymethyl)ethane, triethylene glycol, diethylene glycol,1,2,6-trihydroxyhexane, or trimethylolpropane can also be used as acrosslinking agent.

[0091] The PAG is used in an amount of about 1.0 to about 15% by weightbased on the weight of the base polymer and examples thereof includetriarylsulfonium salts, diaryliodonium salts and mixtures thereof. Also,the organic base is contained in an amount of about 0.01 to about 2.0 wt% on the basis of the total weight of the base polymer and comprises atertiary amine exemplified by triethylamine, triisobutylamine,trioctylamine, triisodecylamine, diethanolamine, triethanolamine, ormixtures thereof.

[0092] In the patterning described in Examples 7 through 11, duringcoating, the thickness of the negative type resist composition coated onthe wafer may vary according to use. Preferably, the thickness of thenegative type resist composition is about 0.2 to about 0.7 μm.Soft-baking is generally performed at about 110 to about 140° C. forabout 60 to about 90 seconds. During exposure, an exposure dose may varyaccording to a deep-UV used. In the case of using ArF or F₂ eximerlaser, energy of about 5 to about 100 mJ/cm² is generally used. The PEBis generally performed at about 100 to about 130° C. for about 60 toabout 90 seconds. The development is generally performed using a 2.38 wt% TMAH (0.26N) solution for about 20 to about 60 seconds.

[0093] According to at least one embodiment of the present invention, apolymer comprising a first repeating unit having a Si-containing monomerunit is provided. The polymer further comprises a second repeating unithaving a hydroxy group copolymerized with the first repeating unit. Thesecond repeating unit may be a monomer unit having a hydroxy group or amonomer unit having an epoxy ring. The polymer having theabove-described structure exhibits high transmittance at shortwavelengths and provides high dry etching resistance by includingsilicon therein. Therefore, the polymer can be used for the manufactureof the negative type resist composition that is advantageously used informing fine patterns.

[0094] Also, the negative type resist composition according to thepresent invention includes an alkali soluble base polymer having arepeating unit formed of a Si-containing monomer unit, a PAG and acrosslinking agent. If the base polymer includes a Si-containing monomerunit and a monomer unit having an epoxy ring, the crosslinking agent isformed of a compound having a hydroxy group. Therefore, in the case ofusing the negative type resist composition according to the embodimentsof the present invention in a BLR process, the density of a resist layeris increased by cross-linkage. Therefore, shrinkage caused by e-beam,which is the most serious problem with conventional positive typechemically amplified resists, is prevented. Also, compared with theconventional positive type resist composition, a negative type resistcomposition according to the present invention has improved adhesion tounderlying layers and easily adjustably wettability.

[0095] Further, the negative type resist composition according to theembodiments of the present invention exhibits high transmittance atshort wavelengths such as a KrF (248 nm), ArF (193 nm), or F₂ (157 nm)eximer laser, and provides high dry etching resistance by includingsilicon therein. Therefore, the negative type resist composition can beadvantageously used in a BLR process. Also, patterns having large aspectratios, which are required for highly integrated semiconductor devices,can be formed using the BLR process in conjunction with the negativetype resist compositions, according to the embodiments of the presentinvention.

[0096] While this invention has been particularly shown and describedwith reference to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A polymer used for a negative type resistcomposition, represented by the following formula:

wherein R₁ is a hydrogen and a methyl group, R₂ is a C₂˜C₈ alkyl grouphaving a hydroxy group, R₃ is a hydrogen atom or methyl group, X is aC₁-C₄ alkyl or alkoxy group, n is an integer from 2 to 4, and q/(p+q) isabout 0.1 to about 0.5.
 2. The polymer of claim 1, wherein the weightaverage molecular weight of the polymer is about 3,000 to about 50,000.3. The polymer of claim 1, wherein R₂ is a 2-hydroxyethyl or a2-hydroxypropyl group.
 4. The polymer of claim 1, wherein X is a methylgroup or a trimethylsilyloxy group.
 5. The polymer of claim 1, furthercomprising at least one repeating unit selected from the groupconsisting of acrylate derivatives, methacrylate derivatives, norbornenederivatives, maleic anhydride monomer derivatives and styrenederivatives, and wherein the Si-containing repeating unit is containedin the base polymer in an amount of about 5 to about 40 mol % based ontotal number of moles of repeating units forming the base polymer.
 6. Apolymer used for a negative type resist composition, represented by thefollowing formula:

wherein R₁ is a hydrogen atom or a methyl group, R₂ is a hydrogen atomor methyl group, X is a C₁-C₄ alkyl or alkoxy group, n is an integerfrom 2 to 4, and q/(p+q) is about 0.1 to about 0.5.
 7. The polymer ofclaim 6, wherein the weight average molecular weight of the polymer isabout 3,000 to about 50,000.
 8. The polymer of claim 6, wherein X is amethyl group or trimethylsilyloxy group.
 9. The polymer of claim 6,further comprising at least one repeating unit selected from the groupconsisting of acrylate derivatives, methacrylate derivatives, norbornenederivatives, maleic anhydride monomer derivatives and styrenederivatives, and wherein the Si-containing repeating unit is containedin the base polymer in an amount of about 5 to about 40 mol % based ontotal number of moles of repeating units forming the base polymer.
 10. Anegative type resist composition comprising: (a) an alkali soluble basepolymer having a first repeating unit represented by the followingformula:

wherein R₁ is a hydrogen atom or a methyl group, X is a C₁-C₄ alkyl oralkoxy group, and n is an integer from 2 to 4; (b) a photoacid generator(PAG); and (c) a crosslinking agent cross linkable by reacting with anacid.
 11. The negative type resist composition of claim 10, wherein thebase polymer has a weight average molecular weight of about 3,000 toabout 50,000.
 12. The negative type resist composition of claim 10,wherein X is a methyl group or a trimethylsilyloxy group.
 13. Thenegative type resist composition of claim 10, wherein the base polymerfurther comprises a second repeating unit having a hydroxy group. 14.The negative type resist composition of claim 13, wherein the secondrepeating unit is represented by the following formula:

wherein R₂ is a hydrogen atom or a methyl group, and R₃ is a C₂˜C₈ alkylgroup having a hydroxy group.
 15. The negative type resist compositionof claim 14, wherein R₃ is a 2-hydroxyethyl or a 2-hydroxypropyl group.16. The negative type resist composition of claim 13, wherein thecrosslinking agent comprises a compound having an epoxy ring.
 17. Thenegative type resist composition of claim 16, wherein the crosslinkingagent comprises triglycidyl isocyanurate, trimethylolpropane triglycidylether or triphenylolmethane triglycidyl ether.
 18. The negative typeresist composition of claim 14, wherein the base polymer furthercomprises at least one repeating unit selected from the group consistingof acrylate derivatives, methacrylate derivatives, norbornenederivatives, maleic anhydride monomer derivatives and styrenederivatives, and wherein the Si-containing repeating unit is containedin the base polymer in an amount of about 5 to about 40 mol % based ontotal number of moles of repeating units forming the base polymer. 19.The negative type resist composition of claim 10, wherein the basepolymer further comprises a second repeating unit having an epoxy ring.20. The negative type resist composition of claim 19, wherein the secondrepeating unit is represented by the following formula:

wherein R₄ is a hydrogen atom or a methyl group.
 21. The negative typeresist composition of claim 19, wherein the crosslinking agent comprisesa compound having a hydroxy group.
 22. The negative type resistcomposition of claim 21, wherein the crosslinking agent comprises1,3,5-tris(2-hydroxyethyl)cyanuric acid,1,1,1-tris(hydroxymethyl)ethane, triethylene glycol, diethylene glycol,1,2,6-trihydroxyhexane or trimethylolpropane.
 23. The negative typeresist composition of claim 20, wherein the base polymer furthercomprises a third repeating unit selected from the group consisting ofacrylate derivatives, methacrylate derivatives, norbornene derivatives,maleic anhydride monomer derivatives and styrene derivatives, andwherein the Si-containing repeating unit is contained in the basepolymer in an amount of about 5 to about 40 mol % based on total numberof moles of repeating units forming the base polymer.
 24. The negativetype resist composition of claim 23, wherein the third repeating unit isa (meth)acrylate derivative or norbornene derivative having a hydroxygroup.
 25. The negative type resist composition of claim 10, wherein thePAG is contained in an amount of about 1.0 to about 15% by weight basedon the total weight of the base polymer.
 26. The negative type resistcomposition of claim 10, wherein the PAG comprises triarylsulfoniumsalts, diaryliodonium salts, or mixtures thereof.
 27. The negative typeresist composition of claim 26, wherein the PAG comprisestriphenylsulfonium triflate, diphenyliodonium triflate,di-t-butyldiphenyliodonium triflate, or mixtures thereof.
 28. Thenegative type resist composition of claim 10, further comprising anorganic base.
 29. The negative type resist composition of claim 28,wherein the organic base is contained in an amount of about 0.01 toabout 2.0 wt % on the basis of the total weight of the base polymer. 30.The negative type resist composition of claim 28, wherein the organicbase comprises triethylamine, triisobutylamine, trioctylamine,triisodecylamine, triethanolamine, or mixtures thereof.
 31. A negativetype resist composition comprising: (a) an alkali soluble base polymerrepresented by the following formula:

wherein R₁ is a hydrogen atom or a methyl group, R₂ is a C₂-C₈ alkylgroup, R₃ is a hydrogen atom or a methyl group, X is a C₁-C₄ alkyl oralkoxy group, n is an integer from 2 to 4 and q/(p+q) is about 0.1 toabout 0.5; (b) a photoacid generator (PAG); and (c) a crosslinking agentformed of a compound having an epoxy ring and cross linkable by reactingwith an acid.
 32. The negative type resist composition of claim 31,wherein the base polymer has a weight average molecular weight of about3,000 to about 50,000.
 33. The negative type resist composition of claim31, wherein R₂ is a 2-hydroxyethyl or a 2-hydroxypropyl group.
 34. Thenegative type resist composition of claim 31, wherein X is a methylgroup or a trimethylsilyloxy group.
 35. The negative type resistcomposition of claim 31, wherein the crosslinking agent comprisestriglycidyl isocyanurate, trimethylolpropane triglycidyl ether ortriphenylolmethane triglycidyl ether.
 36. The negative type resistcomposition of claim 31, wherein the base polymer further comprises arepeating unit selected from the group consisting of acrylatederivatives, methacrylate derivatives, norbornene derivatives, maleicanhydride monomer derivatives and styrene derivatives, and wherein theSi-containing repeating unit is contained in the base polymer in anamount of about 5 to about 40 mol % based on total number of moles ofrepeating units forming the base polymer.
 37. The negative type resistcomposition of claim 31, wherein the PAG is contained in an amount ofabout 1.0 to about 15% by weight based on the total weight of the basepolymer.
 38. The negative type resist composition of claim 31, whereinthe PAG comprises triarylsulfonium salts, diaryliodonium salts, ormixtures thereof.
 39. The negative type resist composition of claim 38,wherein the PAG comprises triphenylsulfonium triflate, diphenyliodoniumtriflate, di-t-butyldiphenyliodonium triflate, or mixtures thereof. 40.The negative type resist composition of claim 31, further comprising anorganic base.
 41. The negative type resist composition of claim 40,wherein the organic base is contained in an amount of about 0.01 toabout 2.0 wt % on the basis of the total weight of the base polymer. 42.The negative type resist composition of claim 40, wherein the organicbase comprises triethylamine, triisobutylamine, trioctylamine,triisodecylamine, triethanolamine, or mixtures thereof.
 43. A negativetype resist composition comprising: (a) an alkali soluble base polymerrepresented by the following formula:

wherein R₁ is a hydrogen atom or a methyl group, R₂ is a hydrogen atomor a methyl group, X is a C₁-C₄ alkyl or alkoxy group, n is an integerfrom 2 to 4, and q/(p+q) is about 0.1 to about 0.5; (b) a photoacidgenerator (PAG); and (c) a crosslinking agent formed of a compoundhaving a hydroxy group and cross linkable by reacting with an acid. 44.The negative type resist composition of claim 43, wherein the basepolymer has a weight average molecular weight of about 3,000 to about50,000.
 45. The negative type resist composition of claim 43, wherein Xis a methyl group or a trimethylsilyloxy group.
 46. The negative typeresist composition of claim 43, wherein the crosslinking agent comprises1,3,5-tris(2-hydroxyethyl) cyanuric acid,1,1,1-tris(hydroxymethyl)ethane, triethylene glycol, diethylene glycol,1,2,6-trihydroxyhexane or trimethylolpropane.
 47. The negative typeresist composition of claim 43., wherein the base polymer furthercomprises a repeating unit selected from the group consisting ofacrylate derivatives, methacrylate derivatives, norbornene derivatives,maleic anhydride monomer derivatives and styrene derivatives, andwherein the Si-containing repeating unit is contained in the basepolymer in an amount of about 5 to about 40 mol % based on total numberof moles of repeating units forming the base polymer.
 48. The negativetype resist composition of claim 47, wherein the base polymer furthercomprises a repeating unit of a (meth)acrylate derivative or norbornenederivative having a hydroxy group.
 49. The negative type resistcomposition of claim 43, wherein the PAG is contained in an amount ofabout 1.0 to about 15% by weight based on the total weight of the basepolymer.
 50. The negative type resist composition of claim 43, whereinthe PAG comprises triarylsulfonium salts, diaryliodonium salts, ormixtures thereof.
 51. The negative type resist composition of claim 50,wherein the PAG comprises triphenylsulfonium triflate, diphenyliodoniumtriflate, di-t-butyldiphenyliodonium triflate, or mixtures thereof. 52.The negative type resist composition of claim 43, further comprising anorganic base.
 53. The negative type resist composition of claim 52,wherein the organic base is contained in an amount of about 0.01 toabout 2.0 wt % on the basis of the total weight of the base polymer. 54.The negative type resist composition of claim 52, wherein the organicbase comprises triethylamine, triisobutylamine, trioctylamine,triisodecylamine, triethanolamine, or mixtures thereof.
 55. A patterningmethod for a semiconductor device comprising: (a) forming a first resistlayer on a layer to be etched on a semiconductor substrate; (b) forminga second resist layer by coating a negative type resist compositioncomprising an alkali soluble base polymer represented by the followingformula:

wherein R₁ is a hydrogen atom or a methyl group, R₂ is a C₂-C₈ alkylgroup, R₃ is a hydrogen atom or a methyl group, X is a C₁-C₄ alkyl oralkoxy group, n is an integer from 2 to 4 and q/(p+q) is about 0.1 toabout 0.5, a photoacid generator (PAG), and a crosslinking agent formedof a compound having an epoxy ring and cross linkable by reacting withan acid; (c) pre-baking the second resist layer; (d) exposing the secondresist layer to light; (e) performing post-exposure baking (PEB) on theexposed second resist layer; (f) forming a second resist layer patternby developing the exposed second resist layer; (g) forming a firstresist layer pattern by etching the first resist layer using the secondresist layer pattern as an etching mask; and (h) etching the layer to beetched using the first resist layer pattern as an etching mask.
 56. Thepatterning method of claim 55, wherein R₂ is a 2-hydroxyethyl or a2-hydroxypropyl group.
 57. The patterning method of claim 55, wherein Xis a methyl group or a trimethylsilyloxy group.
 58. The patterningmethod of claim 55, wherein the crosslinking agent comprises triglycidylisocyanurate, trimethylolpropane triglycidyl ether or triphenylolmethanetriglycidyl ether.
 59. The patterning method of claim 55, wherein instep (d), KrF, ArF or F₂ eximer laser is used for the exposing.
 60. Apatterning method for a semiconductor device comprising: (a) forming afirst resist layer on a layer to be etched on a semiconductor substrate;(b) forming a second resist layer by coating a negative type resistcomposition comprising an alkali soluble base polymer represented by thefollowing formula:

wherein R₁ is a hydrogen atom or a methyl group, R₂ is a hydrogen atomor methyl group, X is a C₁-C₄ alkyl or alkoxy group, n is an integerfrom 2 to 4, and q/(p+q) is about 0.1 to about 0.5, a photoacidgenerator (PAG), and a crosslinking agent formed of a compound having ahydroxy group and cross linkable by reacting with an acid; (c)pre-baking the second resist layer; (d) exposing the second resist layerto light; (e) performing post-exposure baking (PEB) on the exposedsecond resist layer; (f) forming a second resist layer pattern bydeveloping the exposed second resist layer; (g) forming a first resistlayer pattern by etching the first resist layer using the second resistlayer pattern as an etching mask; and (h) etching the layer to be etchedusing the first resist layer pattern as an etching mask.
 61. Thepatterning method of claim 60, wherein X is a methyl group ortrimethylsilyloxy group.
 62. The patterning method of claim 60, whereinthe crosslinking agent comprises 1,3,5-tris(2-hydroxyethyl)cyanuricacid, 1,1,1-tris(hydroxymethyl)ethane, triethylene glycol, diethyleneglycol, 1,2,6-trihydroxyhexane or trimethylolpropane.
 63. The patterningmethod of claim 60, wherein in step (d), KrF, ArF or F₂ eximer laser isused for the exposing.